The DELAY attribute indicates that the archived redo logs at the standby site are not available for recovery until the specified time interval has expired. The time interval is expressed in minutes, and it starts when the redo log is successfully transmitted and archived at the standby site.

When the standby database is in managed recovery mode, redo logs are automatically applied when they arrive from the primary database. However, to protect against the transfer of corrupted or erroneous data from the primary site to the standby site, you might want to create a time lag between archiving a redo log at the primary site and applying that archived redo log at the standby site.